Added fonts suporting new xscreensaver dialoguebox and added lubuntu-grub-theme.
Summary: Added xfonts-efont-unicode which is needed for new xscreensaver dialogue box and lubuntu-grub-theme so that it gets installed by default.
Check that xscreensaver loads without any warnings.
Check if lubuntu-grub-theme gets installed and selected by default on new installations.
Reviewers: kc2bez, wxl, tsimonq2
Reviewed By: wxl
Differential Revision: https://phab.lubuntu.me/D66